35mm/DOF Adapter

Zacatac927 · Post by **Zacatac927** » Sat Apr 21, 2007 1:02 am

Ok, i have been waiting for this topic to come up on this board, but no one seems to care. But the 35mm adapter (i took this off wikipedia, cause im too lazy to type what i know... and cause i know it)

Depth-of-field adapter or DOF adapter is used with digital video camcorders to achieve optical film-like shallow depth of field A DOF adapter could theoretically be used on a multitude of platforms The name 35mm adapter is perhaps more common, since the current designs use a focusing screen the size of 35mm film, but will not be used here since it is theoretically possible to create an adapter of a different size, such as medium format.

how it works
Possibly one of the most impressive characteristics of a DOF adapter is its apparent simplicity. Since most digital camcorders available today have CCD receptors that are too small to facilitate professional depth of field (an XL2 has three chips just 1/3" in size each), a DOF adapter looks to take the place of the camera's CCD and use a larger focusing plate (in many cases, 35mm) to capture an image. Since this image is focused onto a translucent screen (similar to how one would look at a focused image through a system camera's viewfinder), the camcorder is able to frame this intermediate screen and record it. The principle of one of these adapters is similar to pointing a video camera at a movie screen. The lens attached to the adapter now takes the job of the camcorder's focusing and aperture mechanisms, as the camcorder's only responsibility at this point is to record what is being projected onto the focusing screen

construction

A basic DOF adapter usually has four components: a macro lens, an optional plano-convex lens (sometimes a fresnel lens), a translucent focusing screen, and finally a photographic lens of the user's choice. On camcorders without sufficient macro capability, a macro lens, preferably an achromatic doublet (to minimize chromatic aberration), is usually attached directly to the camcorder so that the camcorder can zoom in and focus on the focusing screen. Without the macro lens, certain camcorders would be unable to zoom in well enough to frame the entire focusing screen and still achieve sharp focus. The optional plano-convex lens is used to avoid vignetting in the image. The focusing screen is where the photographic lens image is projected. The screen must be placed at precisely the correct distance from the flange focal mount of whatever lens is being used (most popularly the Canon FD or Nikon F mount), referred to as the depth of focus. Finally, the front lens is a photographic or cinema lens that projects the image desired onto the focusing screen.

but i have been searching for the DIY plans for months coming up with such designs as

http://www.mediachance.com/dvdlab/dof/index.htm
http://www.jetsetmodels.info/pics/basic_35mm_dof.pdf
http://www.dvinfo.net/conf/forumdisplay.php?f=70

and a ton more...

What i just don't understand on here, with limited exceptions in my mind, no one on matthawkins uses the techniques of making you films look like they were shot on film... with using tha adapter's or film look effects... even color correction i don't see... and i don't understand why... it makes your looks and productions value go way up... i have had (seriously) people watch my films and ask how i got the money for film, then id spill it and say i shot on video... and tell them my process...

Lets build adapters!

kene555 · Post by **kene555** » Sat Apr 21, 2007 1:10 am

I've been using the XL2, and taking advantage of its depth of field.

Gyro · Post by **Gyro** » Sat Apr 21, 2007 1:14 am

Reason why not a lot of amatuer filmmakers use mini 35mm adapters is the cheapest one is about $600. And 35mm lenses that attach to it, probably the cheapest one is about that much. I've gripped a couple of films that have used mini35 adapters, this latest one entitled, "The Rising" a zombie TV series, they DoP had a HVX with a Redrock M2 Mini-35mm adapters--we jibbed this thing with a 200mm lens over a 8 story building, was pretty awesome.

Here's a little clip from it, about mid clip you can see me dolly gripping.

http://trees-mom.com/onset.html

kene555 · Post by **kene555** » Sat Apr 21, 2007 1:26 am

So you guys use iMovie for this film?

Gyro · Post by **Gyro** » Sat Apr 21, 2007 1:29 am

Huh? Oh, some random person made that video I just showed you. Nah... I'm pretty sure it'll be edited in a studio.

Zacatac927 · Post by **Zacatac927** » Sat Apr 21, 2007 1:29 am

Gyro wrote:Reason why not a lot of amatuer filmmakers use mini 35mm adapters is the cheapest one is about $600. And 35mm lenses that attach to it, probably the cheapest one is about that much. I've gripped a couple of films that have used mini35 adapters, this latest one entitled, "The Rising" a zombie TV series, they DoP had a HVX with a Redrock M2 Mini-35mm adapters--we jibbed this thing with a 200mm lens over a 8 story building, was pretty awesome.

Here's a little clip from it, about mid clip you can see me dolly gripping.

http://trees-mom.com/onset.html

i see your point, but i gave links to ones DIY ones that cost no more than 100-150, and lenses you can use any old lens you find off a still camera

Gyro · Post by **Gyro** » Sat Apr 21, 2007 1:31 am

Generally you can rent them farely cheap as well.

Zacatac927 · Post by **Zacatac927** » Sat Apr 21, 2007 1:34 am

yeah... ive seen an hvx with redrock micro go for 2,500 a week

but yeah they can be cheap...

maj_barnes · Post by **maj_barnes** » Sat Apr 21, 2007 1:36 am

This looks horribly fake for some reason (I know it's not, but it has a very surreal quality). This is at it's lowest I've seen $799. (iFocus 35mm Adapter for DVX100A)

<object width="425" height="350"><param name="movie" value="http://www.youtube.com/v/f5AEcPWtUgI"></param><param name="wmode" value="transparent"></param><embed src="http://www.youtube.com/v/f5AEcPWtUgI" type="application/x-shockwave-flash" wmode="transparent" width="425" height="350"></embed></object>

kene555 · Post by **kene555** » Sat Apr 21, 2007 1:38 am

And are the DIY one's worth it? I mean, do you have to have special equipment or knowledge to build one, or go somewhere special to get supplies?

Because my filter diameter is 30.5 mm, and I could use one(probably be bigger than my camera though!)

Zacatac927 · Post by **Zacatac927** » Sat Apr 21, 2007 1:40 am

thats nice... thats what id like to have.... i am ready to build one, just need to find the time

kene555 · Post by **kene555** » Sat Apr 21, 2007 1:41 am

I like the effect that adapter has on the vid, but is it worth $800?!

That's pretty extreme for amateur filmmaking - I could never afford that - it's more than my editing computer!

Zacatac927 · Post by **Zacatac927** » Sat Apr 21, 2007 1:43 am

http://www.mediachance.com/dvdlab/dof/index.htm

^^ follow these plans kene... they have yielded the best results from others

kene555 · Post by **kene555** » Sat Apr 21, 2007 1:50 am

Looks good, and this will work for cameras of any lens diameter?

What regular stores can I go to in order to get the optics for this?

Zacatac927 · Post by **Zacatac927** » Sat Apr 21, 2007 1:52 am

i got my macro lens from bhphoto for 14 bucks, then realized i don't need it with my cam... it will fit most cameras... they do have designs out there for specifically xl2's

kene555 · Post by **kene555** » Sat Apr 21, 2007 1:57 am

I won't use it for the XL2, that's my school's camera. I would use it on my Panasonic PV-GS39 palmcorder if possible.
Maybe I could get funding from the school to outfit the XL2 with one.

Gyro · Post by **Gyro** » Sat Apr 21, 2007 2:02 am

Why would the XL2 need one? It's got detachable lenses.

Zacatac927 · Post by **Zacatac927** » Sat Apr 21, 2007 2:03 am

yeah, ok what i did, i have the pana gs180... go to http://pana3ccduser.com/forumdisplay.php?f=15 and search that, it should yield something on your type of camera and how to attch a DOF adapter to it...

kene555 · Post by **kene555** » Sat Apr 21, 2007 2:09 am

OK...will do

Knightly · Post by **Knightly** » Sat Apr 21, 2007 4:11 am

I made the mediachance one as well. I'm pretty happy with the results...just trying to figure out how to get it closer to my camera. The minimum focal distance on a Canon XL1s is quite long for this purpose. I built a rod system to go underneath it to lock it all together.

The benefit of using a 35mm adaptor is not just being able to use different lenses, the benefit is to be able to get the type of Depth of field effect you're getting on your XL2 with the camera a block and a half away zoomed in all the way...but in a wide shot and having the camera closer so the wind doesn't become camera wobble when running at the extreme telephoto of the lens.

Shallow depth of field is all well and good, but if the only way you can achieve it is to sacrifice your framing options, then it's really just applicable to extreme closeups and has no place whatsoever if you want to show something happening in the background blurred out as the background becomes so magnified that you can't discern any of it anyway.

ALove · Post by **ALove** » Sat Apr 21, 2007 7:50 am

Theres a common misconception among people that sensor size influences DOF.

The only things that influence DOF are focal length, aperture, and distance from subject. The reason 35mm traditionally is regarded with has a shallower DOF is because the lenses used are actually a longer lens. In order to be a telephoto at 35mm sensor sizes, a 80+mm lense has to be used. On my DVX, with it's 1/3inch chips, telephoto is about 10+mm.

Picture this...

-------------------
|.......................|
|.......................|
|.......................|
--------------------

Above is our 35mm frame.

-------------------
|.......................|
|........[....]........|
|.......................|
--------------------

In the above, that little square is the 1/3inch chip. Now a 50mm lense would be a lot more telephoto on that, as the focus area isn't as large.

Basically, the XL2 would still need an adapter, but the cool thing is they can attach a smaller achromat, and then focus on the screen.

Zacatac927 · Post by **Zacatac927** » Sat Apr 21, 2007 2:46 pm

Knightly wrote:
Shallow depth of field is all well and good, but if the only way you can achieve it is to sacrifice your framing options, then it's really just applicable to extreme closeups and has no place whatsoever if you want to show something happening in the background blurred out as the background becomes so magnified that you can't discern any of it anyway.

but seeing as this is what hollywood goes through on every shoh, i doubt its that bad

kene555 · Post by **kene555** » Sat Apr 21, 2007 3:43 pm

The only time depth of field is used, really, is during conversation and simple, slow paced shots. Not in action scenes.

So it would be useful to use at times, just not during action scenes, but all else.

DAZMAN · Post by **DAZMAN** » Sat Apr 21, 2007 5:05 pm

I have a redrock m2 adapter with a PL and a Nikon Flange. I use Nikon 28, 35, 50, 135, 200mm lenses, if any one has a Nikon, manual/prime 85mm lenses and is selling it cheap then let me know.

Knightly · Post by **Knightly** » Sat Apr 21, 2007 5:45 pm

That's a technical consideration mostly though, in action shots it doesn't tend to be used due to the fact that some one has to try to keep the shot in focus. Easy when people are hitting marks and they're all pre-measured, not so easy when you're flipping a car or throwing things at people.

As far as Focal length being part of the DoF equation, the physics of light determine that the aperture and the Distance to subject are the only two determining factors for DoF. Field of view (either through capture plane size or focal length or both) merely emphasizes the blurriness outside the single plane of focus through magnification.

The problem is that when you try to emulate DoF by zooming in, the background becomes indistinguishable not because it's blurry, but because the tree a quarter mile away from the subject now has leaves that are the size of the subject's head due to the magnification of the zoom (which is arguable the same as shrinking the capture plane [see text graphic above

]). Changing Focal length on either format accentuates the Circles of Confusion outside the acceptable field of focus by magnifying them. The background (and anything outside the single plane of sharp focus) is always blurry, it's just not obviously blurry unless you magnify it. Since Digital is premagnified due to the size of the capture plane, capture plane size becomes a significant factor.

In order to keep the type of framing you want to convey your story (i.e. Anything other than XCU in digital) and focus the viewers attention, you are left with choosing uninteresting backgrounds or using old painting tricks (which you're using anyway...right?) like leading lines, thirds, heroic vectors and chiarascura/color palette.

With a 35mm adaptor, you can get your out of focus background with a tree that seems to be the size of a tree in a mid-full shot of your subject...so you can argue the semantics of this with me all day long, and say that technically this and technically that, but the fact remains that to have a given framing, the two differ...and all the math becomes rubbish in the face of seeing the result on the screen.

The drawback to haing a 35mm adaptor is that you have to focus much more than digital filmmakers are used to doing...not so much a set it and forget it operation anymore. Blocking and rehearsal becomes much more important.